Microsoft has made Windows 8's final release available to MSDN and TechNet subscribers, so if you are one of those - have fun. The 90-day trial has also been released, so us mere mortals can have a go at it as well. The evaluation version is Windows 8 Enterprise, so it contains a number of features regular users normally won't see. As far as I can tell - it's a bit unclear - the trial version cannot be upgraded to a final version a few months down the line. Happy testing!

Interesting that PAE is mandatory which will probably mean that any drivers targeting Windows x86 and looking for certification will have to be PAE compatible - I wonder what pushed that, customers wanting to keep with Windows x86 but needing support for more than 4GB?

PAE is enforced as many companies still have to work with 16bit PLC devices with correspongind software and the 64bit systems does not support that. So this is just a way to enforce that the drivers are compatible with PAE. You might say that dosbox or some virtualization might do the trick, and indeed in some cases it will, but some devices and industrial hardware indeed need direct contact.

It is not only about the ram size, but also about the exact placement of registers available with old un-updated software (Siemens, i hate you for being the biggest culprit in this) in direct access to the named industrial hardware. In PAE 32+extra bits the initial bits for the conventional memory is in the same place, in a x64bit system this is not always the case.